Lecture 8: Joint Structure

Question 1

General Cartilage Composition

Answer 1

• Collagen fibres in a ground substance
• Chondrocytes live in lacuna
• Nutrients diffused through matrix when joint moves

Question 2

Describe the structure of hyaline cartilage

Answer 2

• Collagen fibres are barely visible

- High water content in matrix

Question 3

Describe the function of hyaline cartilage

Answer 3

• Resist compression
• Provide smooth frictionless surface
• Moulds where there’s articulation

Question 4

Describe the structure of Fibrocartilage. Give examples

Answer 4

• Collagen fibres bundled in matrix
• Orientation of fibres aligns with stresses
• eg. meniscus in knee joint deepens articulation

Question 5

Describe the function of Fibrocartilage

Answer 5

• Resists compression and tension

- Can adapt shape based on stresses

Question 6

What is bony congruence? What effect does it have on soft tissue?

Answer 6

• The bone surfaces that articulate
• More soft tissue is needed where there is less bony congruence, to enable movement
• More BC = stable joint (hip)

Question 7

Describe the function of the meniscus

Answer 7

• Contains concave discs of fibrocartilage
• Deep articulation = more surface area for articulation and movement
• Spreads weight over higher area

Question 8

What is a joint?

Answer 8

• Holds bones together
• Found where bones meet / articulate
• Involves soft tissue
• Allows free / controlled movement

Question 9

What happens when the meniscus is moved?

Answer 9

• Weight is concentrated on a smaller area

Question 10

What type of joint is found in the intervertebral disc?

Answer 10

• Fibrocartilage (between disc bodies)

Question 11

Why is fibrocartilage found between vertebral discs and not hyaline cartilage?

Answer 11

• Disc is attached to outside of vertebral bodies

- When we move our torso we need bones to be held together (tensile forces)

Question 12

What is the nucleus pulposus?

Answer 12

• The inner core of the vertebral disc made of gel-like substance
• Moves like a ball bearing, helping to resist compressing forces

Question 13

What are some features of tendons and ligaments?

Answer 13

• DFCT
• Collagen (aligned to wear stresses are)
• Fibroblasts + (cytes)
• Function = Resist tension
• Able to heal self but very VERY slowly compared to bone

Question 14

Describe the function of ligaments and give an example

Answer 14

• Bone to bone
• Restrict movement
• Movement is restricted “away from itself”
• eg. ankle joint - lateral resists adduction

Question 15

Describe the function of tendons and give examples

Answer 15

• Muscle to Bone
• Function = facilitate and control movement
• Contraction
• eg. contracting biceps, tendon at distal end inserts into radius, pulls bone, in posterior part of hand insert into phalanges, calcaneus tendon (achilles heel)